Book section

ABSTRACT

An improved book section has a plurality of leaves joined by an adhesive thread. The thread is typically coated with an adhesive bonding agent and is heatable by indirectly applied energy. The leaves are stitched together with strands of the thread which are fused together and to the leaves.

el er, Jr. et al. Feb. 4, 1975 [5 BOOK SECTION 2,579,488 12/1951 Freeman 156/272 x 2 607,614 8/1952 Wiser 281/21 [75] inventors: W1ll1am C. Heller, Jr., 1840 N. 3560 290 2 l 71 S d 5 Fatwa Ave. Milwaukee Wis 9 en or etal 6/227 @3202; g g f FOREIGN PATENTS OR APPLICATIONS rotor 1,048,847 11/1966 Great Britain 281/21 R [73] Assignee: said Heller, by said Shatzkin [22] Filed: Feb. 26, 1973 Primary Examiner-Lawrence Charles [21] A 1 No 335 486 Attorney, Agent, or FirmAndrus, Sceales, Starke &

pp Sawall Related U.S. Application Data [62] Division of Ser. No. 74,270, Sept. 22, 1970, Pat. No.

3,730,805. [57] ABSTRACT [52] U.S. Cl 281/27, 57/153, 57/164 An improved k Section has a plurality of leaves [51] Int. Cl B42d l/00 joined y a a esi e thread. The thread is typically [58] Field 61 Search 281/21, 27; 156/93, 380, coated with an adhesive bonding agent and is bearable 156/272; 219/47; 57/153, 164 by indirectly applied energy. The leaves are stitched together with strands of the thread which are fused to- [56] References Cited gether and t0 the leaves.

UNITED STATES PATENTS 2,087,480 7/1937 Pitman 156/380 x 8 Claims 7 Drawmg Flgures BOOK SECTION CROSS REFERENCE TO RELATED APPLICATION This application is a divisional application of copending application, Ser. No. 74,270, filed Sept. 22, 1970, now U.S. Pat. No. 3,730,805.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to the field of book binding and more particularly to an improved book section.

2. Description of the Prior Art A common technique for joining the sheets, or leaves, of a multi-page book is by sewing the paper or film leaves along the center fold thereof. When the number of leaves which are sewn along a common center fold exceed approximately 16, difficulty is encountered in having the pages lie flat when the completed book is open. For this reason, when a large number of pages are to be incorporated in the completed book, the leaves are normally separated into groups of approximately 16 leaves termed signatures or sections. Each signature is then sewn along a center fold and to the adjacent signatures to form the body of the completed book.

In accordance with prior art structures, the leaves of the signature and the assembled signatures are sewn together with one or more strands of thread to form the book body. The aligned signature center folds of the book body are coated with glue to lock the loose ends of the thread and to permit enough glue to seep into the sewing holes to keep the strands of thread stationary with respect to the sewing holes and the signature leaves.

It has been found that such a structure is less than completely satisfactory, particularly for books which receive rigorous or excessive usage, such as childrens books or library reference books. During usage of the book, individual ones of the threads may become separated from the bundle of strands, as by snagging or stretching. Or, the glue holding the strands stationary with respect to the sewing holes and signature leaves may fail due to insufficient glue or seepage thereof. Either of these conditions causes the stitches to loosen and the leaves to separate. The glue holding the thread ends locked may fail, causing the same fault. The sewing holes in the leaves may become enlarged due to the sawing action of a tautened thread or through use of the book after the breakage of the bond between the thread and the sewing holes and signature leaves. Once the above failures arise, continued use of the book has a degenerative effect resulting in failure of the sewn seam or joint and release of the leaves. The joint can be repaired only the completely rebinding the book to include removal of the body of the book from the case, separation of the signatures or sections, resewing the damaged signature, rebinding the signatures, and casing the assembled signatures back into the case of the book. Naturally, this is an expensive and time consuming process which could be eliminated if strong sturdy sewn joints could be obtained in the signature.

One expedient is to saw either the individual leaves or the signatures, sideways rather than along the center fold. This is commonly called side stitching. By this technique, the strands of the thread are not exposed when the book is in use. While this will alleviate the problem to some extent, the user of the book must continually hold his place or the book will snap shut. This failing is particularly objectionable in childrens books since even the older child may have difficulty in maintaining the book in the open position.

SUMMARY OF THE INVENTION It is, therefore, the object of the present invention to provide an improved book section containing a strong sewn joint which may be subjected to rigorous usage without failure.

It is a further object of the present invention to provide an improved book section, the leaves of which are sewn along the center fold and which is capable of withstanding hard usage.

Another object of the present invention is to provide an improved book section having a sturdy joint which utilizes, insofar as possible, conventional book binding techniques, thereby permitting the use of existing book binding equipment.

Briefly, the present invention employs a thread having a period of exterior adhesiveness responsive to exposure to a selected form of indirectly applied energy. The period of adhesiveness may be thermally induced and the thread treated so as to be heatable upon exposure to the energy. The leaves are sewn together, as along the centerfold, with the stitches of the treated thread. The thread is then exposed to the selected form of indirectly applied energy to heat the thread and induce the period of adhesiveness therein. The stitches of the thread become fused together to prevent the sepa' ration of the strands or freeing of the loose thread ends which has heretofore initiated failure of the sewn joint. The strands may also be bonded to the sewing holes and to the leaf portions between the holes to prevent enlargement of the holes or destruction of the leaf portions.

The thread may be formed of a material of thermally responsive adhesiveness or may be coated with a bonding agent having such properties.

In the alternative, the thread may be uncoated and the bonding agent applied to the leaves prior, or after, sewing with a heatable thread.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of a book section or signature having the leaves thereof joined by stitching at the center fold in the conventional manner;

FIG. 2 is a perspective view of book body joined by side stitching;

FIG. 3 is a partially cut away perspective view of an adhesively coated and heatable thread which is incorporated in the book section of the present invention;

FIG. 4 is a perspective view illustrating several steps in a process for forming the book section of the present invention;

FIG. 5 is a perspective view similar to FIG. 4, also il- I lustrating several steps in the forming process;

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to FIG. 1, there is shown therein, a book section or signature l0, sewn in the conventional manner. Signature is formed of paper sheets or leaves 12 containing a centerfold 14 along which the individual leaves are joined by stitches 16 of thread 18.

The centerfold portion of signature 10 is shown in greater detail in FIG. 6. As indicated in that Figure, a plurality of strands of thread 18 pass through holes 22 in centerfolds 14 of leaves 12 in a running stitch, the stitch being repeated on both sides of signature 10.

It will be appreciated that a snagging or tautening of one of strands 20 will enlarge holes 22 in leaves 12, loosening the leaves and that a loosening of the stitches of thread 18 will also loosen the leaves. Each of these conditions leads to a failure of the sewn joint.

To overcome the foregoing problem, leaves 12, either in the folded or unfolded condition, may be sewn by stitches 24 through the rear edges, i.e. side stitched, as shown in FIG. 2 so that the rear edges of the leaves are held tightly together. While, as noted supra, this will prevent loosening of the stitching or leaves, it also prevents the facile handling of leaves 12 obtained by sewing on the centerfold, as shown in FIG. 1.

To overcome the aforementioned short comings of the prior art, the present invention contemplates the use of a thread 18 having a period of exterior adhesiveness responsive to exposure to a selected form of indirectly applied energy. The exposure typically results in a temperature increase so that the period of adhesiveness may be said to be thermally induced. It is also desirable that the adhesive qualities of the thread exist for only a short period of time during, or after, the exposure, so that the thread is fast setting or has a short open time.

A thread of external adhesiveness may be formed, as shown in FIG. 3, by coating a twisted or braided filament 26 with an adhesively thermoplastic or thermosetting bonding agent 28. In the alternative, filament 26 may itself be selected from a substance which has the desired thermally induced adhesive qualities. The bonding agent may be applied in the liquid form or may be granular or powered material which is affixed to filament 26. A typical bonding agent of the thermoplastic type which has been found useful for coating the filament is a water emulsion of ethylene vinyl acetate sold under the trade designation Aircoflex 400 by the Air Reduction Company of New York, NY. The period of adhesiveness, or open time, of such a bonding agent upon termination of the application of heat, it on the order of one second. A thermosetting bonding agent comprised of an epoxy having a cure rate proportional to temperature may be used. An uncoated but externally adhesive thread may be formed of a nylon or a polyvinyl chloride filament.

In connection with the heating properties of thread 18, by the term indirectly applied energy it is meant that the energy responsible for the temperature increases is applied through the medium of a radiant field, rather than by direct application of, for example, a heated body. Typically, the radiant fields are electric or magnetic fields. Thread 18 may be so heatable by dispersing in bonding agent 28, or impregnating in filament 26, a material 30 susceptable to heating by the indirectly applied energy. The material is preferably in the particulate form and is incorporated in the bonding agent or filament in quantities sufficient to produce the desired heating action. When added to the bonding agent or to an adhesive filament this is typically 10 to percent by weight with respect to the bonding agent or filament. Such material, termed herein a susceptor, may be responsive to the indirect application of energy in the form of an alternating magnetic field, in which case the susceptor could consist of material heatable by induction heating, such as particles of iron oxide, preferably gamma Fe O Metal or ferrite particles may also be used. The material may be responsive to an alternating electric field in which case a dielectrically heatable substance such as polyvinyl chloride may be used.

In the alternative, the filament material itself may be susceptable to heating by the indirectly applied energy. For example, a coated or uncoated filament of polyvinyl chloride may be used.

To form the book section of the present invention,

leaves 12 are arranged so that the portions thereof to be sewn together are in alignment. Preferably this involves creasing each of leaves 12, at centerfold 14 and then stacking the folded leaves so that the centerfolds are aligned along a common centerfold, as shown in FIG. 1.

The stacked leaves 12 having aligned centerfolds are then sewn together with thread 18 in the usual manner. The sewing operation may be proceded by a drilling operation which drills holes 22 or the holes may be formed by the sewing needle. While running stitches 16 are shown in FIGS. 1 and 5, it will be appreciated that other types of stitches, such as a machine stitch, may be used, if desired. One or more strands 20 may be incorporated in each stitch 16. At the completion of the sewing, the thread 18 may be out if only a single signature is being assembled or the sewing operation may be continued to sew other signatures and bind the assembled signatures together.

Thread 18 is then exposed to indirectly applied energy, as by inserting the common centerfold 14 of leaves 12 into a radiant field. In the instance in which susceptor 30 is inductively heatable, an alternating magnetic field may be established by coils 32, shown in FIG. 4, energized by the current of alternating voltage source 34. Coils 32 may be cooled by coolant circulated in passages 36 and may be mounted on coil supports 38 which serve as pressure platens.

Upon insertion in the field of coils 32, the susceptor 30 increases in temperature causing the thread to enter the adhesive state and commence the fusion process. During the time thread 18 is in the adhesive state, i.e. during the open time of the thread, pressure may be applied to centerfold 14 by moving coil supports 38 in the direction shown by the arrows in FIG. 4. The pressure application may continue until the termination of the period of adhesiveness of thread 18 and until the adhesive is set. In the case of thermoplastically adhesive thread, removal of centerfold 14 from the field of coils 32, or the turn off of alternating current initiates the termination of the period of adhesiveness.

The exposure of threads 18 of stitches 16 to the magnetic field, and the resulting adhesive condition thereof, fuses the individual threads 18 into a unitary bundle thus preventing individual threads from being snagged or tautened. See FIG. 7. It further locks threads 18 together at each point where they cross so that the loose ends of threads 18 are secured at the points of contact with other threads.

The bonding agent 28 also tends to flow at holes 22 where the threads 18 pass through leaves I2 and acts to bond one leaf to another and threads 18 to leaves 12 at holes 22. This bonding at holes 22 acts to reduce the amount of shifting of one leaf against another which normally causes enlargement of holes 22 and loosening of stitches 16. See FIGS. 6 and 7. Bonding agent 28 also acts to reinforce the edges of holes 22 to further discourage enlargement of holes 22. Threads 18 may also be bonded to leaves 12 along centerfold l4 between holes 22 to further reinforce the sewn seam.

If desired, the exposure of the thread to the applied energy may occur after formation of the book body, or even after the body is cased into the cover.

In the case in which thread 18 is subjected to dielectric heating, the centerfold 14 of signature 10 may be placed in an electric field created by electrodes 40 energized by alternating current voltage source 42. Platens 38 may be incorporated in electrodes 40 as shown in FIG. 5. The remaining steps of the process proceed as described in connection with FIG. 4.

In a modification of the present invention, the bonding agent 28 may be preapplied to leaves 12 at centerfolds 14 prior to or after assembly of signature l0 and a heatable thread 18 for example, formed of a filament of dielectrically heatable material, used for sewing.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

We claim:

1. A book signature comprising:

a plurality of paper leaves having abutting portions containing aligned holes;

a plurality of strands of thread having dispersed therein a gamma Fe O particulate susceptor heatable upon exposure to an alternating magnetic field, said strands being formed into leaf joining stitches running through said holes and along. the abutting portions of said leaves; and

a bonding agent of thermally responsive adhesiveness fusing said strands together and to adjacent areas of said abutting portions.

2. The book section according to claim I further defined as comprising a stack of centerfold leaves having the centerfolds aligned and containing said holes.

3. The book section according to claim I wherein said thread is coated with a bonding agent of thermally responsive adhesiveness for fusing the strands.

4. The book section according to claim 3 wherein said thread is coated with a bonding agent of thermoplastic adhesiveness.

5. The book section according to claim 3 wherein said thread is coated with a bonding agent of thermosetting adhesiveness.

6. The book section according to claim 3 wherein a deposit of said bonding agent lies between said leaves adjacent said aligned holes.

7. The book section according to claim l wherein said thread contains 10 to 50 percent by weight of dispersed particulate susceptor.

8. The book section according to claim 1 wherein said abutting portions of said leaves contain a deposit of a thermally responsive adhesive on the areas of said abutting portions adjacent said strands which is fused to said strands. 

1. A book signature comprising: a plurality of paper leaves having abutting portions containing aligned holes; a plurality of strands of thread having dispersed therein a gamma Fe2O3 particulate susceptor heatable upon exposure to an alternating magnetic field, said strands being formed into leaf joining stitches running through said holes and along the abutting portions of said leaves; and a bonding agent of thermally responsive adhesiveness fusing said strands together and to adjacent areas of said abutting portions.
 2. The book section according to claim 1 further defined as comprising a stack of centerfold leaves having the centerfolds aligned and containing said holes.
 3. The book section according to claim 1 wherein said thread is coated with a bonding agent of thermally responsive adhesiveness for fusing the strands.
 4. The book section according to claim 3 wherein said thread is coated with a bonding agent of thermoplastic adhesiveness.
 5. The book section according to claim 3 wherein said thread is coated with a bonding agent of thermosetting adhesiveness.
 6. The book section according to claim 3 wherein a deposit of said bonding agent lies between said leaves adjacent said aligned holes.
 7. The book section according to claim 1 wherein said thread contains 10 to 50 percent by weight of dispersed particulate susceptor.
 8. The book section according to claim 1 wherein said abutting portions of said leaves contain a deposit of a thermally responsive adhesive on the areas of said abutting portions adjacent said strands which is fused to said strands. 